It's not realistic to 'get in touch with the game company' and let them know. Most people wouldnt know where to begin getting in touch with a studio.
I also agree posting links to the person you suspect on a SL forum is bad juju.
However in a case like the one presented, finding a screenshot of the game you think it's stolen from like you did is a fantastic idea, but it's LL you should send this information to directly. They have an entire legal team who can look into proving this claim for you. If you dunno how to get in touch with them, I'm sure you can find it somewhere on help, or in an FAQ!
Or evenon the forums, just, when you ask, don't give such specific examples! Could have easily enough just said. "How do I report someone I suspect of copyright infringment!"
Cheeeeerz!